Increased radio-frequency power absorption in human tissue due to coupling between body coil and surface coil tech./dosim.

By: Boesiger P, Buchli R, Saner M, Meier D
Published in: Ann N Y Acad Sci 1992; 649: 160-165
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Exposure

Exposure Parameters
Exposure 1: 64 MHz
Modulation type: pulsed
Exposure duration: 15 min

Exposure 1

Main characteristics
Frequency 64 MHz
Type
Exposure duration 15 min
Modulation
Modulation type pulsed
Duty cycle 2.6 %
Additional info

repetition time 500 ms echo time (6 echos): 50-300 ms
Exposure setup
Exposure source
  • 1.5 T whole body imager
Setup coil placed concentrically on the face of the phantom (2 cm high, r = 6 cm) in such a way that coil center and phantom center coincide
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 11.7 µT - measured - from the transmitting radio-frequency
magnetic flux density 12 µT - calculated - without surface coil
magnetic flux density 14 µT - measured - without surface coil
magnetic flux density 112 µT - calculated - with surface coil with mechanical tuning capacitors
magnetic flux density 94 µT - measured - with surface coil with mechanical tuning capacitors
magnetic flux density 6 µT - measured - with surface coil with variocaps
SAR 0.3 W/kg - calculated - from transmitting B-field
SAR 24 W/kg - calculated - from induced B-field